Fabrics obtained by weaving warps and wefts have conventionally been used widely as an industrial fabric. They are, for example, used in various fields including papermaking wires, conveyor belts and filter cloths and are required to have fabric properties suited for the intended use or using environment. Of such fabrics, a papermaking wire used in a papermaking step for removing water from raw materials by making use of the network of the fabric must satisfy a severe demand. There is therefore a demand for the development of fabrics which do not transfer a wire mark of the fabric and therefore have excellent surface property, have enough wear resistance and rigidity and therefore are usable desirably even under severe environments, and are capable of maintaining conditions necessary for making good paper for a prolonged period of time. In addition, fiber supporting property, improvement in a papermaking yield, good water drainage property, dimensional stability and running stability are demanded. In recent years, owing to the speed-up of a papermaking machine, requirements for papermaking wires become severe further.
Since most of the demands for industrial fabrics and solutions thereof can be understood if papermaking fabrics on which the most severe demand is imposed among industrial fabrics will be described, the present invention will hereinafter be described by using a papermaking fabric as a representative example.
For papermaking fabrics, excellent surface property not permitting transfer of wire marks of the fabric to paper, fiber supporting property for supporting fine fibers, wear resistance enough to permit long-period running even under severe running conditions, running stability ensuring stable running until the final using stage and rigidity are very important. Research on the design or constitution of the fabric capable of satisfying the above-described properties is proceeding. Recently, two-layer fabrics using, as a portion of upper surface side warps and lower surface side warps which are vertically arranged pairs, a warp binding yarn which is woven with both an upper surface side weft and a lower surface side weft to form an upper surface side surface and a lower surface side surface and at the same time, has a binding function have come to be used. A two-layer fabric using a warp binding yarn is also disclosed in Japanese Patent Laid-Open Publication No. 2003-342889. This fabric has excellent surface property, because it uses a warp binding yarn and does not use an additional binding yarn which destroys the upper surface side fabric design. In the fabric disclosed in this document, however, a lower surface side weft constituting a lower surface side fabric has a design in which it passes over two warps and then passes under two warps so that no long crimp of the lower surface side weft is formed on the lower surface side surface and the fabric does not have excellent wear resistance. In general, a fabric has improved wear resistance when a lower surface side weft is imparted with a long crimp design. In a fabric using a warp binding yarn, the fabric design is sometimes limited, depending on the yarn diameter, structure or using purpose of the fabric, or the like. For example, the fabric disclosed in Japanese Patent Laid-Open Publication No. 2003-342889 has a design, on the lower surface side fabric, in which a lower surface side weft passes over two warps and then passes under two warps. In this fabric, a water drainage space is formed between a set of lower surface side warps which are adjacent to each other.